#include <iostream>
using namespace std;

int main()
{
    int n;
    while(cin >> n)
    {
        int a[n];
        for(int i = 0; i < n; i++)
            cin >> a[i];
        int m;
        cin >> m;
        int i = 0;
        for(i = 0; i < n; i++)
        {
            if(m == a[i])
            {
                cout << i << endl;
                break;
            }
        }
        if(i == n)
            cout << "No" << endl;
    }
    return 0;
}
